Grinder fixture



A. C. LINDHOLM. GRINDER FIXTURE. APPLICATION FILED FEB. 17.1921.

Patented May 16, 1922 2 SHEETS-SHEET I.

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A. c. LINDHOLM GRINDER FIXTURE. APPLICATION FILED FEB. II I921.

Patented May 16, 1922.

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Patented, May 16, 1922 Application filed February 17, 1921. Serial No. 445,8 11.

To all whom it may concern:

Be it known that I, ARTHUR C. LIND- I-i'OLM, a citizen of the United States of America, and a resident of Springfield, in the county of Hampden and State of Massachusetts, have inventedv a new and useful Grinder Fixture, of which the following is a specification. I

My invention relates to improvements in attachments for grinding machines, the same consisting of a fixture capable of being attached to a grinding machine, and provided with means for holding a dressing tool or implement for the grinding-wheel of such machine, and with means for holding whlle being ground on such wheel the fixed contact of an ignition timer, and further pro vided with or adapted to have secured thereto a holder for the breaker-arm of such timer, whereby the contact with which such arm is equipped is held in place while be ing ground, all of peculiar construction, together with such otherparts and members as may be necessary or desirable in order to render the attachment or fixture complete in every respect, all as hereinafter set forth.

The flat, juxtaposed'ends of timer contacts become pitted and irregular from use, so that it is necessary from time to time to resurface them, otherwise the operation of the timer is rendered defective and the results produced by said timer are seriously impaired. In grinding the aforesaid ends of timer contacts it is imperative that they be resurfaced exactly alike, or at exactly the same angle so that when the movable con: tact is actuated against the fixed contact the contiguous surfaces of both contacts'are in engagement throughout their entire areas,

which is a task very diflicult to perform by hand and with a file, such being the method and means usually employed m work'of this character.

ture with convenient means for dressing or redressing the grinding-wheel, with. which timerv contacts are to be ground or resurfaced, accurately, easily, andquickly.

Another object is to provide means, in connection with such fixture, for grinding or resurfacing contacts in any ofthe many ignitio'ns' systems, such, for'example, as the Delco, or. the Remay, or the Atwater-Kent ignitions, the first ofrthese being the one selected in this case with which to illustrate the application of the present invention.

Stillanother object is to construct the ture so that it can be used in a chuck which is set at 45' degrees to the grinding face of the grinding-wheel, without adjusting said chuck on its vertical, axial support. This is animportant feature, because it is intended to employ the fixture with a grinder that is set for grinding and adapted to" grind valves, and I am able to grind timer contacts with the same degree of accuracy as the valves are ground, and, as stated, without changing the position of the chuck axially on its vertical support.

Other objects and advantages will appear in the course of the following description.

I attain the objects and secure the advantages of my invention by the means illustrated in the accompanying drawings, in which i Figure 1 is a front end elevation of a fixture which embodies a practical form of my invention, the same being without either the fixed-contact bushing orthe breaker-arm holder, but carrying a dressing-tool for a grinding-wheel; Fig. 2, a top plan of said fixture, showing two timer contacts held in ri'nding or operative position thereby, and itself in place in a grinding machine, portions of which appear in this and the following'views, and also in the first view; Fig. 3, a similar plan to that shown in Fig. 2, except that here the fixed contact, which is in the act of being ground in'Fig. 2, has been removed, and the other contact is in the act of being ground; Fig. 4, a bottom plan. of the fixture; Fig. 5, a front elevation of the fixture without the breaker-arm holder; Fig. 6, a vertical sectional detail through the fixed-contact-holding portion of the fixture, taken on lines 6-6, looking in the direction of the associated arrow, in Fig. 2, and, Fig. 7, an inner end elevation of the fixed-contact bushing.

Similar reference characters designate similar parts throughout the several views.

In the first three views the front end portion of the chuck of a grinding machine is represented at 1, from the front side of the support or bearing 39 of which projects a lug 2 having a thumb-screw 3 tapped into the front end thereof, and there is also represented, at 41 in Figs. 2 and 3, a portion of the grinding-wheel of such machine. A. dressing-tool appears at 5 in Fig. 1, such tool consisting in part of a projection? on one side, in the outer end of which projection is set a diamond or other cutter 8. These parts and members are all of usual and well-known construction.

The grinder, of which the chuck 1 and the grinding-wheel 4: form parts, is designed more particularly for grinding valves, consequently said chuck is positioned at an angle of 415 degrees to the axis of said grinding-wheel, and the axes of these two members are on the same horizontal plane, as is customary in such machines.

The fixture comprises an irregular-shaped block or body 9, which is attachable by means of a rod or shank 10 to the chuck 1, together with a holder, as 11., that is capable of being mounted on and removed from said body. 1 will proceed first to describe in detail the body 9 with its parts, members, and appurtenances which are apart from the holder 1], and then take up for consideration said holder.

The general shape in plan of the body 9 is triangular, one side being in front and the other two sides forming the ends of said body, when the same is in operative position in the grinder. The front or outer and rear or inner edges or ends of the body, 9, if continued to the point of intersection, would form an angle of 15 degrees, and the shank 10 is a horizontal member that extends at the same angle from said rear or inner end. Top and bottom lugs 12 project reaiwvardly or to the right from the body 9 at or adj acent to the front end of the rear or inner edge of said body, a vertical setscrew 13 is tapped into the bot-tom lug 12 from below, and a thumb-screw 14- is tapped into the top lug 12 from above. Having one end abutting the block 9 between the lugs 12, and held within the grip of the setscrew 1.3 and the thumb-screw 141, is a horizontal brace bar 15, said bar being in front of. the shank 10. The latter is received and secured in the chuck 1, while the bar 15 at its rear terminal is received and secured in the lug 2 with the aid of the thumb-screw 8 The 015% of the shank 10 is to support the device as a whole from the chuck 1, and the office of the bar 15 is to assist in steadying said device, and in taking up part of the strain during the dressing and grinding operainner ends of the body 9 is a vertical, V-,

shaped groove 16, and such groove opens at 17 through the front side thereof. A horizontal passage is formed in the body 9 to receive a long bolt 18, said passage opening at the rear end into the groove 16 and at the front end through what I have termed the front side of the body. The bolt 18 is parallel with the outer end of the body 9, and the head of said bolt is at the rear end of the same. 011 the forward, protruding terminal of the bolt 18 is a nut 19. .The bolt 18 is below the horizontal plane of the front opening, slot, or recess 17, and there is a vertical clamp 20 on said bolt to cooperate with the sides of the groove 16 for the purpose of holding the vertical shank of the dressing tool 5 in place.

Normally the clamp 20 is held against the rear edges of the groove 16 by means of the bolt 18 and the nut 19, which latter bears against the contiguous edge or side of the body 9, as appears in Figs. 2, 3, and 4:, but, when the dressing-tool 51s to be used, said nut is turned forwardly on said bolt and the latter with said clamp is pushed rearwardly far enough to admit the shank of said tool into the groove 16 and between the sides of said. groove and the adjacent side of said clamp, the tool being positioned with the projection 7 partially in the recess '17 and protruding beyond said recess. dressingtool 5 may rest at the bottom on the bolt 18, and one side of the projection 7 is in contact with the vertical edge of the recess 17'. After the dressing-tool is thus positioned the nut 19 is screwed tightly against the contiguous edge of the body 9 to draw the bolt 18 forward and force the clamp 20 against the shank of said tool in a manner securely to hold the tool in place.

With the fixture properly attached to'the chuck 1, and the dressing-tool set in said fixture, the diamond 8 is applied to the outer, flat face of the grinding-wheel 4 and such face is dressed in the usual manner.

Upon loosening the nut 19 the dressingtool 5 can be removed from the fixture and laid aside until again needed, and it is at The this time that said nut is actuated to draw axis of the shank 10 and at right-angles to the adjacent face of the grinding-wheel 1- when the fixture is properly supported by the shank in the chuck 1. The barrel of the bushing 23 has a sliding fit in the passage 21, and there is a plurality of longitudinal slots 24. in said barrel, one of which slots extends through a fiango 25 at the outer end of the barrel, as shown at 26 in Figs. t and 7. The bore of the bushing 23 is of a size to receive the shank of a fixed contact '27. The bushing 23 with the contact 27 therein is inserted in thepassage 21, and the set-screw 22 is screweddown thereon with such force as to contract said bushing on said contact and securely hold the parts in the passage.

Since different fixed contacts are of different diameters, it is necessary to provide bushings having bores of correspondingly different diameters; otherwise the bushings are all alike.

A forwardly -extending portion of the body 9 is depressed to form a platform or flat support for the holder 11. li ising from this support, in front of the adjacent end of the shank 10, is a vertical post 26 which is screw-threaded at the upper terminal to re ceive a set-nut 29. The holder 11 consists in part of a fiat plate that is receivable on the supporting portion therefor of the body 9, and is perforated to receive the post 28.

The holder 11 is for a Delco breaker-arm 30 which carries a (movable) contact 31. The hub of the breaker-arm 30 fits onto or over a post 32 that rises from the holder plate near the front, left-hand or outer corner thereof, and said arm extends rearwardly from said post between two upright lugs 33 and the adjacent ends of horizontal set-screw 3 1 and a. horizontal thumb-screw 35 tapped into and through said lugs. he lugs 33 rise from the holder plate back of the vertical plane of the post 32 which plane is parallel with the front edge of said plate, and the set-screw 3 1 is tapped into and through the inner lug and the thumb-screw 35 into and through the outer lug. By means of the post 28, the nut 29, and the setand thumb-screws 3a and 35, the breaker-arm 30 is held securely in place on the holder 11 and may be adjusted thereon.

On the bottom of'the holder 11, adjacent to the front corners thereof, are two lugs 36 and 37, into and through which are tapped set-screws 38-38. The lug 36 with its setscrew 38 is at the left and the lug 37 with its set-screw 38 is at the right. When the holder 11 is in place on the body 9 and with the post 28 projecting through the same, the set-screws 38 are located in position to bear against opposite edges of the forward portion of said body, and said screws are manipulated to adjust said holder in such a manner as properly to present the movable contact 31 for grinding, it being assumed that, through the medium of the set-screw 3st and the thumb-screw 35, the breaker-arm 30 has already been properly adjusted to the same end. The holder 11 is secured on the body 9 by means of the thumb-nut 29 screwed onto the post 38 above said holder. The contact 31 is so positioned that the vertical plane of the outer end thereof which is to be ground is inside or to the right of the vertical plane of the outer end of the contact 27, which is theend of said last-named contact that is to be ground.

Assuming that the fixture is attached to the chuck 1: When the contact 27 and the breaker-arm 30 with its contact 31 are in place, as illustrated in Figs. 2 and 3, said contact 27 is first ground on the grindingwheel 4t 5 then the thumb-screw 22 is loosened and the bushing 23 with said first-named contact is removed from said fixture; nex said contact 31 is ground; and finally said breaker-arm is removed, after loosening'the thumbscrew 35, or the thumb-nut 29 may be unscrewed and the holder 11 taken off be fore removing the breaker-arm. Both contacts are thus ground and in a manner to insure engagement throughout their entire contacting areas, each time the movable contact is actuated into engagement with the fixed contact, provided the proper adjustment be given the breakenarm when it is set preparatory for the grinding operation.

Inasmuch as different types of breakerarms are considerably unlike each other, holders therefor must necessarily be different also, wherefore, I do not intend to limit myself to the particular type of holder herein shown and described, but may use any holder that is adapted to be mounted on and secured to the body 9. r I

Other changes or modifications in matters of shape, size, arrangement, and construe tion may be made in the fixture as a whole without departing from the spirit of my invention or exceeding the scope of what is claimed.

What 1 claim as my invention, and desire to secure by Letters Patent, is-

'1. As an improved article of manufacture, a grinder fixture comprising a body provided with means for holding a contact while being ground, and having a chuckengaging shank extending therefrom.

2. As an improved article of manufacture, a grinder fixture comprising a body provided with means for holding a contact while being ground, and having a chuckengaging shank extending therefrom, the axes of said contact, when in position in said body, and said shank being in angular relationship.

3. As an improved article of manufacture, a grinder fixture comprising a body provided with means for holding a breaker-arm with its contact while the latter is being ground, and having a chuck-engaging shank extending therefrom.

4. As an improved article of manufacture, a grinder fixture comprising a body provided with means for holding a dressingtool for a grinding-wheel, and with means for holding a contact while being ground, and having a chuck engaging shank extending therefrom.

5. As an improved article of manufacture, a grinder fixture comprising a body provided with means for holding a dressingtool for a grinding-wheel, and with means for holding a contact while being ground, and having a chuck-engaging shank extending therefrom, the axis of either the cutting element of said tool, when the latter is secured to said body, or of said contact, when the same is in position to be ground, being in angular relation to the axis of the shank.

6. As an improved article of manufacture, a grinder fixture comprising a body provided with means to have a dressing-tool secured thereto, said body having a chuck engaging shank extending therefrom, and a brace attachable to said body and to the support for the chuck.

7. As an improved article of manufacture, a grinder fixture comprising a body provided with means to have a contact secured thereto, said body having a chuck-engaging shank extending therefrom, and a brace attachable to said body and adapted to be connected with the support for the chuck.

8. The combination, in a grinder fixture, with a body attachable to a chuck, and having a passage therein, of a bushing for a contact, said bushing being receivable in said passage, and means rigidly to secure said bushing with a contact therein in said passage.

9. The combination, in a grinder fixture, with a body attachable to a chuck, and having a passage therein, of a split bushing for a contact, said bushing being receivable in said passage, and a screw tapped into said body and adapted, to hold said bushing in said passage and a contact in said bushing.

10. The combination, in a grinder fixture,

with a body attachable to a chuck, of a removable holder for a breaker-arm with its contact, said holder being attachable to said body, and means to secure said holder-to said body.

11. The combination, in a grinder fixture, with a body attachable to a chuck, of a removable holder for a breaker-arm with its contact, said holder being attachable to said body, means to adjust said holder on said body, and means to secure said holder to said body.

12. The combination, in a grinder fixture, with a body attachable to 'a chuck, of a removable holder for a breaker-arm with its contact, said holder being attachable to said body, and means to secure said holder to said body, such means comprising a post and nut, the holder being perforated to receive said post.

13. The combination, in a grinder fixture, of a body attachable to a chuck, a detachable holder for a breaker-arm with its con tact, a post carried by said body to receive said holder, screws arranged to adjust said holder on said post as an axis, and a nut on said post to secure said holder to said body.

14. The combination, in a grinder fixture, of a body attachable to a chuck, a detachable holder for a breaker-arm with its contact, said holder being attachable to said body, and provided with screws for the adjustment of the breaker-arm, and means to secure said holder to said body. a

15. The combination, in a grinder fixture, of a body attachable to a chuck, a detachable hclder for a breaker-arm with its contact, a post carried by said body to receive said holder, screws arranged to adjust said holder on said post as an axis, screws for the adjustment of said breaker-arm on said holder, and. a nut on said post to secure said holder to said body.

ARTHUR. C. LINDHOLM.

I Witnesses:

F. A. CUTTER, T. F. DWIGHT. 

